I wanted to try out the latest "linear" focusing algorithm and updated kstars to 3.3.9 (RPI 3, Ubuntu, kstars build: 2020-01-02T08:28:54Z). I can not any more move my focuser inwards any more and get a focuser error. This happens both when pressing the "inwards" button and using autofocus (tried all 3 algorithms). Outwards focusing works fine. The inwards button also seem to work for a few clicks when just starting everything up, but then the error comes and it does not work anymore. This is the message in the log:
[2020-01-04T19:29:02.225 CET DEBG ][ org.kde.kstars.indi] - FCUSB1 Focuser : "Error: Invalid range for FOCUS_TIMER_VALUE. Valid range is from 0 to 5000. Requested value is -1000 "
I came from a pre-linear-focusing version where it never gave an error, so maybe this new change introduced the bug?
Sorry, there was a bug in 3.3.9 that results in your issue. It was fixed last night. It only occurs with focusers that cannot move to absolute positions, but clearly, yours is one of those (given the FOCUS_TIMER_VALUE message).
A work-around for now would be using the nightly build
I know that the fix is in the latest code, and it may be in the latest nightly build release, but I'm not sure. For sure by tomorrow.
This bug affects all focuser algorithms, not just the experimental one.
BTW, once things are working for you, I'd love to hear if the new algorithm is an improvement for you. It's still a work-in-progress, though. Make sure you start it up reasonably close to focus (e.g. fine tuning, but not major focus changes). Also, I'd recommend checking the full-field button, and experimenting with the step size.